I love pushing the boundaries with sweet and savory. I, personally, would go for it and just try something unusual like a gorgonzola dolce with some seckel pears, or perhaps an aged goat cheese with tart apples. I have personal experience with pairing chocolate with goat cheese (in brownies), and it is a match made in heaven. I think chocolate cake tends to be pretty 1 dimensional anyway, so a powerful cheese with a sweet finish might just give it more depth.

POLC - both the goat and blue (gorgonzola solve) cheeses sound interesting notes. Since I asked the question this morning I came across a recipe that uses figs, pistachios and stilton...mousse, tuile, multiple sauces, etc....but the flavor profile could be adapted to accompany a cake.